Objective: Assessment of spontaneous pain-like behaviors by analyzing locomotor patterns and gait abnormalities as non-stimulus evoked nociception measures in rodents
Materials & Equipment Checklist
4 items2 from ConductScience
Gather these items before starting the experiment. Check off items as you prepare.
Equipment4
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Protocol Steps
View Abstract
Rodents are commonly used to study the pathophysiological mechanisms of pain as studies in humans may be difficult to perform and ethically limited. As pain cannot be directly measured in rodents, many methods that quantify "pain-like" behaviors or nociception have been developed. These behavioral methods can be divided into stimulus-evoked or non-stimulus evoked (spontaneous) nociception, based on whether or not application of an external stimulus is used to elicit a withdrawal response. Stimulus-evoked methods, which include manual and electronic von Frey, Randall-Selitto and the Hargreaves test, were the first to be developed and continue to be in widespread use. However, concerns over the clinical translatability of stimulus-evoked nociception in recent years has led to the development and increasing implementation of non-stimulus evoked methods, such as grimace scales, burrowing, weight bearing and gait analysis. This review article provides an overview, as well as discussion of the advantages and disadvantages of the most commonly used behavioral methods of stimulus-evoked and non-stimulus-evoked nociception used in rodents.
1
Animal placement and acclimation
Place rodents individually in small cages with mesh or barred floor for testing
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Note: Animals must be tested individually to allow proper assessment of gait and locomotor patterns
View evidence from paper
“Rodents are placed individually in small cages with a mesh or barred floor”
2
Mechanical stimulus application - Manual Von Frey method
Apply monofilament perpendicularly to the plantar surface of the hind paw until it buckles, delivering constant pre-determined force
Note: Plantar surface of hind paw is most commonly used; dorsal surface or abdomen can also be tested. Response is positive if animal exhibits brisk paw withdrawal, licking, or shaking during or immediately after stimulus
View evidence from paper
“A monofilament is applied perpendicularly to the plantar surface of the hind paw until it buckles, delivering a constant pre-determined force (typically 0.2–13.7 mN for mice and 5.9–98 mN for rats) for 2–5 s”
3
Mechanical stimulus application - Electronic Von Frey method
Apply single un-bending filament perpendicularly to hind paw with force increased by rotation of handheld device until paw withdrawal occurs
Note: Force ramp and paw withdrawal force are displayed by software post-test
View evidence from paper
“A single, un-bending filament is applied perpendicularly to the hind paw. The force is increased by rotation of the handheld device until paw withdrawal occurs. The force ramp and paw withdrawal force are displayed by the software post-test”
4
Mechanical stimulus application - Randall-Selitto test
Restrain rodent and place hind paw or tail between pointed probe tip and flat surface, increasing pressure until withdrawal or vocalization occurs
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Note: Pressure is gradually increased until animal responds
View evidence from paper
“The rodent is restrained and the hind paw (or tail) is placed between a pointed probe tip and flat surface. The pressure is increased until withdrawal or vocalization occurs”
5
Observe and record pain-like behaviors
Monitor and document spontaneous pain-like behaviors including reduced ambulation, agitation, increased grooming of affected area, and vocalizations
Not specifiedNot specified
Note: Gait analysis assesses locomotor patterns and gait abnormalities as non-stimulus evoked nociception measures. Behaviors should be scored by investigator blinded to treatment group
View evidence from paper
“pain-like behaviors which can include the withdrawal of a body part from a stimulus, reduced ambulation, agitation, an increase in grooming of the affected area, and vocalizations upon sensory stimulation”
